Originally Posted by Frozen Fireball 
Definitely Arena and Daggerfall. I really like to finish them just for their historical value, but they are way too outdated even for someone like me who plays through pre-2000 games every now and then.
Those 2 are high on my list of games to remake as well. I tried Daggerfall, got to the first town and it was just too archaic for me to enjoy. Remakes of those 2 games would be amazing.
I'll throw out Pizza Tycoon as a game I'd like to see remade. I'm sure there's little demand for a pizza making sim, but it was a fun game back in the day and it would be cool to have an updated version of it.
Oh, another one that would be amazing to remake - Star Control II. I know they made the Ur Quan Masters, but I'd love to see that game remade with today's technology.